Alright people, I've got my hands on more spoilers from Chinese forums.
I make no claim on how accurate all this is, so bear with me:
Spoiler for stuff:
-1st off, Shiage, Accel and Touma exchanged cellphone numbers
-Touma's worried about meeting with other people after being gone for a while. Shiage's answer: get drunk and it'll all be alright.
-Which leads to him running into Mikoto when he's drunk. And also Komoe, Himegami and a lot of others before he got back to his dorm and meet up with Index.
Shiage seems to have gotten in deep S@#% for suggesting that to Touma.
-Tsuchimikado talks with Accel about Freshman.
-List of girls who showed up to the party: Mikoto, Komoe, Kumokawa Seria, Fukiyose, Musujime Awaki, Kazakiri Hyouka, and Maika; they were all eventually persuaded to leave by Bardway's underlings eventually.
-Kaori is launched via a Rocket onto Radiosonde Castle. She fought a magician who modified his own body, and uses Thor's hammer. With one blow by the hammer a third of the (20km diameter) castle will be destroyed. However the hammer cannot work on something not flying so Kaori blew the castle up with St. Peter's spell. That lead to the castle's 2nd plan, dropping down onto Touma and kill him.
-Crisis was averted by Touma, Shiage and Accel working together to destroy the beacons in Academy City locking the Castle's descent onto them, and the castle crashed into the ocean.
-The ones behind all this calls themsleves 'CRIMSON'.
-Next volume's in Hawaii, and Mikoto will have some sort of major role in it.
-The volume seems to end with Mikoto telling Touma he never have to be alone anymore, and she'll be with him no matter what happens from now on. (UNCONFIRMED)